CVT's (Continuously Variable Transmissions) have been, theoretically, the answer to many problems now pressing modern vehicle design. The main advantages being potential improvements in fuel consumption, performance and emissions. CVT's require an extensive new development in transmission technology. Many designs have been proposed, and a number of prototypes built. There are also a small number that have reached production, for example Van Doorne belt driven transmission used in smaller cars powered by engines of approximately 150 to 200 Nm torque. Applications in more powerful cars are the focus of current CVT research. The basic types of CVT's fall into the following categories: Hydrostatic (i.e. hydrostatic pump and motor); Traction (belt or rolling contact); Electric and Ratchet. When any of these transmissions are used independently they have a limited ratio range and have to be of a large capacity to transmit required torque. This can to some extent be overcome by providing a parallel power path as a "boost" system. This creates two systems, one a fixed mechanical route and the second, a continuously variable path which now has a reduced power requirement. These CVT's can become complex since they are based on the technology which is radically different to conventional manual or automatic transmissions and hence require new manufacturing technique. Development programs have also to be extensive to achieve a proven product.
A transmission as described in this invention shows that original targets set for a CVT transmission could be met by use of the existing manual or automatic or combination of both technologies, without having a need to develop new transmission technology. All gears in the present transmission are in a permanent mesh, similar to a modern manual transmission. Gear selecting apparatus has been designed with one part incorporated into a gear itself and second part incorporated into a gear case assembly. These mechanisms are also based on the technology of the existing devices but modified and arranged to form a novel gear selecting apparatus. These mechanisms may be actuated by a hydraulic or hydraulic-electric methods to provide precise and smooth gear shifting. This invention primarily deals with the mechanical aspects of the transmission including the hydraulic gear selecting apparatus.